1) Field of the Invention
The present invention relates generally to exterior rearview mirror assemblies for motor vehicles, and more particularly, to an adjustable support arm having a pivot control unit for resisting uncontrolled rotational movement of the support arm while allowing for infinitely variable position adjustment.
2) Description of Related Art
Rearview mirror assemblies for vehicles, particularly for commercial trucks, exist in a wide variety of shapes and sizes. These various mirror assemblies include many different arrangements for mounting the mirror assemblies on the vehicles. On large, commercial vehicles, such as trucks and buses, mirrors are often secured within mirror housings mounted on a support arm so as to extend the mirror out from the side of the vehicle thereby providing a clear view of different areas around the vehicle. Depending on the size and design of the mirror, as well as the area around the vehicle to be observed, different mounting arrangements have been used. A typical mounting arrangement includes a support arm comprised of a holder bar extending outwardly from the vehicle, often in substantially a U-shape, in which the ends of the U-shaped bar are attached to the side of the vehicle. Alternately, many mirror assemblies for commercial vehicles use a holder bar that may be attached to the vehicle at only one end, with a mirror housing being disposed at a distal opposite end or central portion, or both, of the bar. In either of these applications, mounting bars are typically attached to each side of the driver's cab of a truck, and the mirror housing is attached to the support arm in various ways.
Swivel joints are also now being included in the support arm assembly to make it possible to pivot the mirror to position the mirror at a preferred viewing position, or from an operational position in which the mirror is normally set that is essentially perpendicular to the side of the vehicle, into a storage position wherein the mirror stands essentially parallel to the side of the vehicle. This arrangement makes it possible to fold the mirror into the side of the vehicle during transport and parking decreasing its overall width or to fold the mirror back against the side in order to avoid, or at least diminish damage to the mirror upon collision with an obstacle. The swivel joints are typically designed using detent joints to hold the mirror in one of a few pre-defined operational or storage positions, highly limiting the ability to adjust the position of the mirror for viewing. While providing some flexibility to position the mirror, such swivel joints do not offer a wide range of positions for positioning the mirror assembly. Additionally, the detent systems known in the prior art suffer from significant wear and tear issues that loosen the detent resistance to secure the mirror assembly in the desired position, eventually leading to a shaky and unusable mirror assembly.
Most conventional mounting arrangements, including swivel joint arrangements, suffer from complicated constructions requiring, for instance, adapters, multiple piece connectors, multiple support braces, and a variety of screws, bolts and the like to attach the support arm to the vehicle. Such complicated mounting arrangements are more cumbersome, costly and labor intensive than may be desired. Perhaps more importantly, however, is the fact that many of these assemblies which utilize a multiplicity of connectors are subject to vibration resistance problems that result in loosening of the connections between the various mounting components of the mirror assembly, which leads to mirror shaking and visual impairment.
As noted above, a substantial problem with external vehicle rearview mirrors, particularly in the case of commercial vehicles, is the occurrence of vibration. First, vibration can negatively affect the use of the mirror, and second, vibration of the mirror can lead to damage due to fatigue for nearly every component in the mirror assembly. Over time, wear caused by wind and road vibrations loosens the connections between the various support members which mount the mirror assembly to the vehicle. In many cases, after only minimal wear has occurred on most large mirror assemblies for commercial vehicles, excessive mirror shaking is present in the assembly that significantly reduces effective use of the mirror. The support arms are particularly susceptible to wind and road vibrations due to the heavy loads of supporting the entire mirror assembly, often leading to premature failure and replacement of support member components if not properly installed on the vehicle.
Accordingly, it is an object of the present invention to provide a support arm for a mirror assembly that is infinitely adjustable in position.
It is a further object of the present invention to provide a support arm for a mirror assembly that resists loosening of the assembly components that control pivotal movement of the support arm to prevent unwanted shaking of the mirror assembly.